Page. 

 Fig. 1. Orthis MrcHEUNi var. Nevadknsis 63 



1. A side view of a large specimen. [Beak of ventral valve uot quite arched enougli, 



and the height of the area of the dorsal valve not well shown, in this figure.] 

 1 a. A dorsal view of same. [Figure makes the cardinal area look too wide.] 

 1 6. A side view of a smaller specimen. 

 1 e. A ventral view of same. [Posterior lateral strise too straight in this figure and 1 a.] 



Fig. 2. Hemiphoxites crenistiua 62 



2. A ventral view of an accidentally distorted sjiecimen. 



T'i.g. 3. Productus subhorridus 75 



3. A side view. 



3a. A front view of another specimen. 



3 h. A ventro-auterior view of another example. 



Fig. 4. Productus costatus?? G9 



4 An anterior view ; the shell heing turned so as to show the irregularity of the costse 



on the anterior slope. 

 4 a. A side view. .* 



4 6. A ventral view. 



Fig. 5. PuODtlCTUS SEMIRETICULATUS. ~ 69 



5. View of ventral valvo. 



/ <' >v o «. S 

 Fig. 6. Productus - Iveoi? ' v'. 67 



6. An oblique side view of a large specimen distorted by pressure. 



6 a. A ventral view of another specimen, with its ears and margins broken away. 



6 b. An' external cast of the dorsal valve, with some portions of the shell remaining near 



the cardinal margin, showing the thick marginal ridge, and a part of the cardinal 

 ' process, with the small mesial ridge, which latter is divided near the cardinal pro- 

 cess, as in P. scahriculus. 



Fig. 7. Productus Prattenianus 72 



7. A ventral view of an imperfect specimen, with the ears and free margins broken 



away. 



7 a. A side view of another imperfect specimen. 



Fig. 8. Productus semistriatus 74 



8. An autero- ventral view. 



8 a. A side view of same. 



